Two Phase I trials conducted by Novavax in healthy adults administered with A/H5N1 avian influenza vaccine candidate, either alone or with one of two undisclosed adjuvants, have met primary objectives.

The randomised, observer-blind trials demonstrated the safety and immunogenicity of differing doses of the vaccine, achieved statistically significant adjuvant effects on the immune responses and observed no vaccine-related serious adverse events.

Novavax president and CEO Stanley Erck said the results demonstrate that the company can produce antigens from avian influenza strains that are at least as immunogenic as any other described in published results to date.

"Importantly, as we accelerate our development activities, these results give us tremendous flexibility for pursuing pandemic vaccine products, including vaccines directed at population segments that are sensitive to adjuvant use," Erck said.

"The trials demonstrated the safety and immunogenicity of differing doses of the vaccine, achieved statistically significant adjuvant effects on the immune responses and observed no vaccine-related serious adverse events."

The two dose-ranging, placebo-controlled trials were carried out under the US Department of Health and Human Services' Biomedical Advanced Research and Development Authority contract.

The hemagglutination inhibition assay responses against the vaccine virus at day 42 indicated that the adjuvanted vaccines stimulated strong immunogenicity at even the lowest (3.75µg) dose tested.

Both the trials satisfy CBER criteria for accelerated approval since the unadjuvanted vaccine elicited HAI titers = 40 in >82% of subjects at a dose of 45µg.

The HAI titers =40 in more than 52% of subjects against the drifted virus were also elicited by the unadjuvanted vaccine.

Novavax senior vice president and chief medical officer Dr Gregory Glenn said; "We have reviewed the preliminary top-line results of these trials and believe that achieving similar immune responses to our vaccine in future clinical trials, regardless of which of the two adjuvants is used, if any, would meet the immunogenicity criteria for accelerated approval of a pandemic influenza vaccine set by CBER."